Field of the Invention
The present disclosure relates to an image reading apparatus and a control method for the image reading apparatus capable of simultaneously reading both sides of a document.
Description of the Related Art
Conventionally, in an image reading unit included in a copying machine or a facsimile machine, or a scanner for inputting data to a computer, an image reading apparatus (an automatic two-sided reading apparatus) for automatically reading image information of both the front and back sides of a sheet document without the intervention of a user is used. Examples of this automatic two-sided reading apparatus include an apparatus in which image sensors are provided on both sides of a document conveying path for front and back sides, thereby automatically reading both sides of a document in a single conveyance of the document. In a document read by such an automatic two-sided reading apparatus, the positional relationship between a reading reference end and an image reference end of the document may be different between the front and back sides, depending on the type of the document orientation (vertically long or horizontally long) or the opening direction of the document (top-bottom opening or left-right opening). See FIGS. 8B and 9A described below.
For example, in a case where an actual document size is larger than a document size specified as a reading setting by a user, and if the above positional relationship is different between the front and back sides, the range of a valid image on the back side is different from that on the front side. Thus, it is not possible to acquire a desired image by a method similar to that for the front side.
Thus, to obtain a desired output result by reading images of such a two-sided document, it is necessary to provide output taking into account the relationship between a front side image and a back side image, such as outputting a back side image corresponding to the output position or the output range of a front side image.
Japanese Patent Application Laid-Open No. 2005-268893 discusses a technique for simultaneously reading images on front and back sides and performing an image conversion process on each side in real time according to the relationship between the front side image and the back side image, thereby generating image data. According to Japanese Patent Application Laid-Open No. 2005-268893, it is possible to obtain an output result in a desired form without reducing productivity.
However, an automatic two-sided reading apparatus discussed in Japanese Patent Application Laid-Open No. 2005-268893 simultaneously reads the front and back sides of a document while performing an image conversion process on each side, thereby outputting read image data in real time. Thus, in the technique discussed in Japanese Patent Application Laid-Open No. 2005-268893, it is necessary to include hardware resources such as a processor capable of executing image conversion processes on front and back sides in parallel, and a document size detection sensor for automatically detecting a document size before the start of reading images. As described above, in the technique discussed in Japanese Patent Application Laid-Open No. 2005-268893, it is necessary to include the above hardware resources. This leads to a complex configuration. Thus, it is difficult to prevent an increase in manufacturing cost.